The invention discloses a rapid assessment method for performance indexes of different emergency control measures in an electric power system, and belongs to the technical field of the electric power system and automation thereof. According to a transient calculation model of the electric power system, candidate emergency control information and time domain simulation data when no control is implemented, and the electromagnetic power of an emergency control moment synchronous machine is calculated directly after different candidate emergency control measures are implemented, thereby rapidly determining the variation in difference between the electromagnetic power and the mechanical power of a single machine infinite-bus equivalent machine under different emergency control measures at the emergency control moment. Furthermore, the increment of a retardation area under different emergency control measures is calculated based on an extended equal area criterion, thereby determining the performance indexes of the different emergency control measures. The rapid assessment method disclosed by the invention can be applied to offline emergency control strategy calculation or online pre-decision emergency control measure calculation, thereby being conducive to optimization and coordination among the different emergency control measures, improving the transient stability of the system, and improving the economy and the safety of operations of the electric power system.